Conventionally, in case a dynamic fluid pressure bearing mechanism is employed in a spindle motor (hereinafter referred to as a “motor”), the boundary between a lubricant filled in the dynamic fluid pressure bearing mechanism and an ambient air is formed within a gap of tapering shape to prevent leakage of the lubricant. In the dynamic fluid pressure bearing mechanism of this structure, it is typical that an oil-repellent agent is applied on portions close to a lubricant level to thereby form an oil-repellent film. Japanese Patent Application Publication No. 2004-289957A discloses a technique of forming an oil-repellent film by applying an oil-repellent agent solution composed of an oil-repellent agent dissolved in a solvent on a shaft and heating the oil-repellent agent solution within an oven to remove the solvent.
An adhesive agent is used for affixing various parts of a motor. For example, Japanese Patent Application Publication No. 2006-191735A discloses an outer rotor type spindle motor in which a rotary drive magnet is adhesively bonded to the inner circumferential surface of a rotor frame. A highly reactive adhesive agent such as an epoxy-based adhesive agent that is rapidly curable at a room temperature, one-component epoxy adhesive agent or the like is used as an adhesive agent. The adhesive agent is cured by heating the rotor frame with a high-frequency induction heating device. Further, Japanese Patent Application Publication No. 2004-15955A discloses a method in which an adhesive agent is applied on a stator core (i.e., an armature) or a fixing portion of a frame (a base portion of a motor) to which the stator core is to be mounted. The stator core is placed on the fixing portion, and then, an electric current is allowed to flow through the stator core so that a conductive wire generates heat. The adhesive agent is cured by use of the heat thus generated.
However, in case the parts of a motor applied with an oil-repellent agent are heated within an oven, it is time-consuming to elevate the temperature. This reduces the productivity and becomes an obstacle in automating a manufacturing process. Moreover, the production facilities grow large. Similarly, when the parts of a motor are affixed using a thermally curable adhesive agent, the task of heating them within an oven is time-consuming and becomes an obstacle in automating a manufacturing process.
Meanwhile, it is sometimes the case that the bonding portion of a circuit board attached to the base portion of a motor is sealed with a resin in order to secure insulation. The base portion is subjected to pre-heating if the resin used at this time has a low flowability. However, it also takes a large amount of time to pre-heat the base portion using a hot plate.
Further, in case of using the high-frequency heating as disclosed in Japanese Patent Application Publication No. 2006-191735A, an eddy current concentrated on the surface region is generated in the heated parts, which heats the surface region only. Consequently, a steep temperature variation occurs between the interior region and the surface region of the parts, which leads to a thermal deformation of the parts (namely, distortion or dimensional change in the parts).